Nonfogging sulfurized cutting oils



United States Patent 3,256,195 NONFOGGING SULFURIZED CUTTING OILS James R. Dickey, Elizabeth, and Mervin F. Troutman,

Wayne, N .J., assignors to Esso Research and Engineering Company, a corporation of Delaware No Drawing. Filed Dec. 31, 1962, Ser. No. 248,222 5 Claims. (Cl. 25248.6)

This invention concerns improvements in sulfurized cutting oils and is particularly directed to the modification of such oils to make them less hazardous to machinists and other workers employing them.

Cutting oils are used principally in metal working where roughing cuts are being made. The primary object in this step is to remove major amounts of material so that only relatively small amounts of metal remain to be removed more carefully by the finishing cut. There is ordinarily an enormous pressure between the cutting edge of the tool and the metal being machined. This requires that the lubricant that is used be capable of providing lubrication even under heavy loads. The cutting oil must also function to dissipate heat from both the tool and the work. In addition, it serves to washa-way the chips. For these reasons the cutting oil is normally used in copious quantities and is poured over the work in a steady stream. Most cutting oils in commercial use comprise various types of sulfurized or sulfochlorinated hydrocarbons or fatty oils. I

Because of the need for a large quantity of cutting oil during a metal cutting operation, the oil isoften sprayed at high pressure into the cutting zone. It has been found that this frequently causes a phenomenon known as fogging. This is a term that is applied to the condition that exists when small particles of hydrocarbons or other components of the cutting oil form as a result of the oil splashing under high pressure and these particles become suspended in the air surrounding the cutting machine. The fogging of the cutting oil is recognized as an unsafe condition because of the possibility that the machine operator can inhale excessive amounts of hydrocarbons along with harmful sulfur and/ or chlorine compounds. There is of course the additional hazard that the fogging of the cutting oil could lead to a dangerous fire.

It has now been found, in accordance with the present invention, that the fogging of sulfurized cutting oil in those instances where it is sprayed onto the work under high pressure can be greatly reduced by incorporating in the cutting oil from about 0 .3 to about 2 wt. percent of an oil-soluble copolymer prepared from three types of monomers, one being an ester of a C to C aliphatic alcohol and an alpha,betaunsaturated dicarboxylic acid, the second monomer being an alkylene ester of a short chain fatty acid, and the third component being an anhydride of an unsaturated dibasic acid, particularly maleic anhydride. The preferred alpha,beta-unsat-urated dicarboxylic acid is fumaric acid, although esters of maleic acid or of itaconic acid may be used. The alkylene esters include vinyl, isopropenyl and allyl esters of acetic, propionic and butyric acids, i.e. esters of C to C fatty acids and C to C unsaturated aliphatic alcohols.

The three monomers that are employed in preparing the tripolymers of the types mentioned above may be used in the portions set forth below:

Specific examples of aliphatic alcohol esters of alpha,beta-unsaturated dicarboxylic acids that may be used in these terpolymers include: octyl itaconate, octadecyl maleate, lauryl fumarate, lauryl maleate, tallow fumarates, tallow maleates, and C or C oxo alcohol fumarates or maleates.

By tallow fumarates or tallow maleates is meant the esters of fumaric acid or maleic acid and the alcohols derived from tallow by hydrogenation or by sodium reduction. The tallow alcohols are principallyC to C alcohols with minor amounts of C to C and C alcohols. The oxo alcohols are well known in the art and can be prepared from olefins by reaction with carbon monoxide and hydrogen in the presence of a suitable catalyst,

as for example, a cobalt carbonyl. The reaction products from the later reaction are primarily aldehydes having one more carbon atom than the starting olefins. These aldehydes are then hydrogenated in a separate catalytic stage to convert them to the corresponding alcohols.

The preferred dicarboxylic acid anhydride that is used in the terpolymers is maleic anhydride. The preferred alkylene ester is vinyl acetate. The preferred aliphatic ester of an alpha,beta-unsaturated dicarboxylic acid comprises C to C alcohol fumarates.

The copolymers employed in this invention may be prepared by any well-known polymerization process. Particularly preferred is a polymerization conducted in the presence of peroxide type catalysts or other free radical catalysts. These include: benzoyl peroxide, acetyl peroxide, urea peroxide, and tertiary butyl perbenzoate. Such catalysts are used in concentrations in the range of from about 0.01 to about 3 wt. percent. The polymerization may be carried out in a suitable solvent in order to control reaction velocity and molecular weight. Such solvents include: benzene, heptane, and mineral oil. Oxygen may be excluded during the polymerization by the use of a blanket of an inert gas such as nitrogen or carbon dioxide. Polymerization temperatures may range from about F. to about 230 F. and reaction time may vary from about 3 to about 7 hours. The final copolymer may have a molecular weight in the range of from about 5000 to about 500,000. For convenience in blending at the termination of the polymerization reaction, the polymer may be diluted with a light mineral oil and then stripped of solvent and unconverted monomers to give a concentrate of the polymer.

The cutting oils to which the copolymers may be added in accordance with the present invention are those known as sulfurized cutting oils. hydrocarbon oils and hydrocarbon oils to which various sulfurized materials have been added, such as sulfurized Such oils include: sulfurized fatty oils, sulfurized solvent extracts of mineral oils, sulfurized esters, sulfurized olefin polymers, and the like. The sulfurization is usually accomplished with free sulfur or with sulfur monochloride or with a combination of these agents. The sulfurization of a mineral hydrocarbon oil may be effected, for example, by adding elemental sulfur thereto and heating to 250300 F. or higher. In some instances it is merely necessary to add the sulfur to the mineral oil at a temperature high enough to melt the sulfur, stir the sulfur into the oil, and then cool the mixture.

An animal or vegetable oil such as sperm oil, lard oil, cottonseed oil, peanut oil, or the like, may similarly be sulfurized by adding sulfur thereto, as for example, 6 to .12% sulfur, and heating at a temperature in the range of say 300 to 375 F. for 1 to 3 hours. The sulfurization of the fatty oil may be accomplished in the presence of the fatty oil alone, in which case the sulfurized product is subsequently blended with a mineral lubricating oil, or alternatively, the fatty oil may be sulfurized in the presence of the mineral lubricating oil.

The cutting oils to which the present invention is particularly directed are those containing in the range of from 0.2 to 1 Wt. percent of elemental sulfur and which may have other added sulfurized organic materials to increase the total sulfur content to a maximum not exceeding about 5 wt. percent.

Although a wide range of lubricating oils may be employed as base stocks for the cutting oils, in general the base oil will comprise an oil having a viscosity at 100 F. in the range from about 90 to 500 Saybolt Seconds, an API gravity of from about 23 to about 33, and a flash point above about 300 F. Preferably, a light coastal petroleum oil or naphthenic petroleum oil having a viscosity at 100 F. from about 100 to about 300 SUS is used.

Among the sulfurized materials that may be employed in preparing cutting oils in accordance with the present invention are included: the sulfurized esters of abietic acid described in U.S. Patent 2,217,764, the sulfurized solvent extracts of petroleum fractions described in U.S. Patents 2,222,643 and 2,227,952, the sulfurized olefin polymers described in U.S.Patent 2,246,282, and the sulfurized oils prepared in accordance with U.S. Patents 2,- 246,282 and 2,467,137. It is to be understood, of course, that the invention is not limited to these particular types of materials.

The following examples serve to illustrate the manner in which the present invention may be practiced.

EXAMPLE 1 A mineral lubricating oil concentrate of a terpolymer comprising fumarate esters, vinyl acetate, and maleic anhydride was prepared using the following proportions:

Tallow fumarate, grams 76.7 C oxo alcohol fumarate, grams 156.7 C oxo alcohol fumarate, grams 100.0 Vinyl acetate, grams 195.5 Maleic anhydride, grams 10.8 Tert. butyl perbenzoate, ml. a 2.2 Mineral oil diluent, grams 94 The fumarate esters and the mineral oil diluent were charged to a 2-liter flask and heated under an atmosphere of nitrogen until the esters had dissolved in the mineral oil. Then the vinyl acetate, maleic anhydride, and tertiary butyl perbenzoate were added and the mixture was heated under reflux with stirring. When it had been determined by polarographic analysis that the fumarate esters had disappeared, the mixture Was diluted with a sufficient quantity of a solvent neutral mineral oil (150 SUS viscosity at 100 F.) to give (after removal of unreacted monomers) a final polymer concentrate containing about 40 wt. percent of polymer. Excess vinyl ace tate was removed by heating at a temperature in the range of 175 to 210 F. while purging with nitrogen.

EXAMPLE 2 A sulfurized cutting oil was prepared by dissolving at about 250 F., with stirring, about 1 wt. percent of elemental sulfur in a naphthenic oil having a viscosity of about 145 SUS at 100 F. and then blending 92.5% of the sulfurized naphthenic oil with 7.5% of mixed fatty oils that had been treated with sulfur monochloride to a content of about 8% sulfur and 8% chlorine.

EXAMPLE 3 To a portion of the cutting oil of Example 2 there was added a quantity of the polymer concentrate of Example 1, the proportion being 1 volume of the polymer concentrate to 55 volumes of the cutting oil, thus providing about 0.7 wt. percent of polymer in the cutting oil.

EXAMPLE 4 EXAMPLE 5 Blends were prepared' containing, respectively, 1 vol. percent and 2 vol. percent of the polymer concentrate of Example 1 in the cutting oil of Example 2. The viscosities of these blends and of the cutting oil without the added polymer were determined. The measured viscosities are given in Table I.

TABLE I Measured Viscosity, Saybolt Universal Seconds Oil Composition 100 F. 210 F. Example 2 104. 2 39. 5 Example 2 plus 1% Example 1 Concentrate 81. 9 38. 3 Oil of Example 2 plus 2% Example 1 Concentrate 94. 5 39. 9

The data in Table I indicate that although polymers of the type represented by that of Example 1 are known to be lubricating oil thickeners, i.e. they normally raise the viscosity, at the concentrations employed here the polymer tended to reduce the viscosity of the sulfurized cutting oil. This indicates that the fogging reducing action of the polymer was not the result of raising the viscosity of the oil.

It will be understood that the examples herein presented are for the purpose of illustrating the invention and that there is no intention of limiting the scope of the invention thereto. The invention is to be defined by the appended claims.

What is claimed is:

1. An improved sulfurized cutting oil having reduced tendency to form a fog when sprayed upon metal being worked which comprises a major proportion of a hydrocarbon lubricating oil, in the range of from 0.2 to 1 wt. percent of sulfur derived from added elemental sulfur, and from about 0.3 to about 2 wt. percent of a polymer prepared from 50 to wt. percent of an ester of an 1alpha,beta-un-saturated dicarboxylic acid and a C to C aliphatic alcohol, from about 20 to 50 Wt. percent of an ester of a C to C fatty acid and a C to C unsaturated aliphatic alcohol, and from about 1 to 5 wt. percent of an anhydride of an unsaturated dicarboxylic acid.

2. Improved cutting oil as defined by claim 1 wherein said terpolymer is prepared from mixed C to C alcohol esters of fumaric acid, vinyl acetate and maleic anhydride.

3. Improved cutting oil composition as defined by claim 1 containing additional sulfur furnished by an added sulfurized organic constituent selected from the group consisting of sulfurized esters and sulfurized hydrocarbons, the composition having a maximum total sulfur content of about 5 Wt. percent.

4. Improved cutting oil composition as defined by claim 3 wherein at least a portion of the additional sulfur is furnished by a sulfur-monochloride-treated fatty oil.

5. Improved cutting oil composition as defined by claim 1 wherein said mineral lubricating oil is an oil References Cited by the Examiner UNITED STATES PATENTS 4/1949 Leland 252-48.6 3/1963 Agius et a1. 252-56 10 DANIEL E. WYMAN, Primary Examiner.

L. G. XIARHOS, Assistant Examiner. 

1. AN IMPROVED SULFURIZED CUTTING OIL HAVING REDUCED TENDENCY TO FORM A FOG WHEN SPRAYED UPON METAL BEING WORKED WHICH COMPRISES A MAJOR PROPORTION OF A HYDROCARBON LUBRICATING OIL, IN THE RANGE OF ROM 0.2 TO 1 WT. PERCENT OF SULFUR DERIVED FROM ADDED ELEMENTAL SULFUR, AND FROM ABOUT 0.3 TO ABOUT 2 WT. PERCENT OF A POLYMER PREPARED FROM 50 TO 80 WT. PERCENT OF AN ESTER OF AN ALPHA, BETA-UNSATURATED DICARBOXYLIC ACID AND A C8 TO C20 ALIPHATIC ALCOHOL, FROM ABOUT 20 TO 50 WT. PERCENT OF AN ESTER OF A C2 TO C4 FATTY ACID AND A C2 TO C3 UNSATURATED ALIPHATIC ALCOHOL, AND FROM ABOUT 1 TO 5 WT. PERCENT OF AN ANHYDRIDE OF AN UNSATURATED DICARBOXYLIC ACID. 